galaxies Archives

January 25, 2023January 25, 2023 by Evan Gough

According to Simulations, the Milky Way is One in a Million

A lonely Milky Way analogue galaxy, too massive for its wall. The background image shows the distribution of dark matter (green and blue) and galaxies (here seen as tiny yellow dots) in a thin slice of the cubic volume in which we expect to find one of such rare massive galaxies. Credit Images: Miguel A. Aragon-Calvo. Simulation data: Illustris TNG project Licence type Attribution (CC BY 4.0)

Humanity is in a back-and-forth relationship with nature. First, we thought we were at the center of everything, with the Sun and the entire cosmos rotating around our little planet. We eventually realized that wasn’t true. Over the centuries, we’ve found that though Earth and life might be rare, our Sun is pretty normal, our Solar System is relatively non-descript, and even our galaxy is one of the billions of spiral galaxies, a type that makes up 60% of the galaxies in the Universe.

But the Illustris TNG simulation shows that the Milky Way is special.

January 18, 2023January 18, 2023 by Evan Gough

The Donut That Used To Be a Star

This sequence of artist's illustrations shows how a black hole can devour a bypassing star. 1) A normal star passes near a supermassive black hole in the center of a galaxy. 2) The star's outer gasses are pulled into the black hole's gravitational field. 3) The star is shredded as tidal forces pull it apart. 4) The stellar remnants are pulled into a donut-shaped ring around the black hole, and will eventually fall into the black hole, unleashing a tremendous amount of light and high-energy radiation. Credit: NASA, ESA, Leah Hustak (STScI)

The death of a star is one of the most dramatic natural events in the Universe. Some stars die in dramatic supernova explosions, leaving nebulae behind as shimmering remnants of their former splendour. Some simply wither away as their hydrogen runs out, billowing into a red giant as they do so.

But others are consumed by behemoth black holes, and as they’re destroyed, the black hole’s powerful gravity tears the star apart and draws its gas into a donut-shaped ring around the black hole.

January 18, 2023January 18, 2023 by Nancy Atkinson

You’re Looking at a Map of the Milky Way’s Magnetic Field

Colour shows the polarized microwave emission measured by QUIJOTE. The pattern of lines superposed shows the direction of the magnetic field lines. Credit: The QUIJOTE Collaboration.

Using telescopes that study the sky in the microwave part of the electromagnetic spectrum, astronomers have successfully mapped the structure of the magnetic field of the Milky Way galaxy. While magnetic fields are difficult to measure in space, an international team of astronomers used the Teide Observatory on Tenerife in the Canary Islands to conduct 10 years of observations.

January 17, 2023January 11, 2023 by Paul M. Sutter

Using the Shadows of Clusters to Measure the Universe

Artist's impression of a quasar and a relativistic jet emanating from the center. Credit: NASA

Astronomers have begun using a sophisticated suite of simulations, an advanced machine learning model of the formation of galaxy clusters, and an exotic relationship between galaxies to understand the origins of dark matter and dark energy.

January 12, 2023January 11, 2023 by Paul M. Sutter

Astronomers Begin to Understand Strange “Backsplash” Galaxies

SMACS cluster from JWST shows evidence of dark matter — The galaxy cluster SMACS 0723 as seen by NIRCam on JWST. It's gravitational lensing properties (from its mass and from the mass of dark matter) are helping astronomers identify 88 distant galaxies in this field of view for further study. Courtesy NASA, ESA, CSA, STScI

Clusters of galaxies do not appear in an instant. Instead they gradually form through the accumulation of many galaxies. But when galaxies fall in they don’t just stop moving. Instead, they keep moving around. These are called backsplash galaxies, and astronomers are using them to help understand the formation history of their home clusters.

January 10, 2023January 10, 2023 by Evan Gough

The James Webb Links Modern Green Pea Galaxies to Ancient Galaxies in the Cosmic Dawn

A trio of faint objects (circled) captured in the James Webb Space Telescope’s deep image of the galaxy cluster SMACS 0723 exhibit properties remarkably similar to rare, small galaxies called “green peas” found much closer to home. Image Credit: NASA, ESA, CSA, and STScI

When the James Webb Space Telescope lifted off from Earth on Christmas Day in 2021, it carried a lot of expectations with it. One of its scientific goals is to seek the light from the first galaxies in the Universe and to study how galaxies form and evolve.

A new paper shows that the JWST is doing just that and has found a link between the first galaxies and rare galaxies in our backyard that astronomers call “Green Pea” galaxies.

January 10, 2023January 10, 2023 by Carolyn Collins Petersen

Newly Found Stars are Technically in the Milky Way, but They’re Halfway to Andromeda

This illustration shows the Milky Way galaxy's inner and outer halos. A halo is a spherical cloud of stars surrounding a galaxy. (Image Credits: NASA, ESA, and A. Feild [STScI]) — This illustration shows the Milky Way galaxy's inner and outer halos. A halo is a spherical cloud of stars surrounding a galaxy. A population of RR Lyrae variables in the halo is giving clues to its distance. (Image Credits: NASA, ESA, and A. Feild [STScI])

We all know our galaxy, the Milky Way, is big. Really big. But, exactly how far out does it extend? Where are the outer limits? Astronomers aren’t exactly sure, precisely. However, a study of galaxies in the Virgo Cluster accidentally turned up a population of stars in the outer part of the Milky Way. They may answer those questions.

December 23, 2022December 23, 2022 by Evan Gough

Webb’s New Image Reveals a Galaxy Awash in Star Formation

This JWST image shows NGC 7469, a luminous, face-on spiral galaxy approximately 90 000 light-years in diameter that lies roughly 220 million light-years from Earth in the constellation Pegasus. Image Credit: ESA/Webb, NASA & CSA, L. Armus, A. S. Evans

When a spiral galaxy presents itself just right, observations reveal more detail. That’s the case with NGC 7469, a spiral galaxy about 220 million light-years away. It’s face-on towards us, and the James Webb Space Telescope captured its revealing scientific portrait.

December 21, 2022December 21, 2022 by Evan Gough

Webb Stares Deeply Into the Universe, Showing How Galaxies Assemble

This image represents a portion of the full PEARLS field, which will be about four times larger. Thousands of galaxies over an enormous range in distance and time are seen in exquisite detail, many for the first time. Image Credit: SCIENCE: NASA, ESA, CSA, Rolf A. Jansen (ASU), Jake Summers (ASU), Rosalia O'Brien (ASU), Rogier Windhorst (ASU), Aaron Robotham (UWA), Anton M. Koekemoer (STScI), Christopher Willmer (University of Arizona), JWST PEARLS Team IMAGE PROCESSING: Rolf A. Jansen (ASU), Alyssa Pagan (STScI)

The James Webb Space Telescope is delivering a deluge of images and data to eager scientists and other hungry-minded people. So far, the telescope has shown us the iconic Pillars of Creation like we’ve never seen them before, the details of very young stars as they grow inside their dense cloaks of gas, and a Deep Field that’s taken over from the Hubble’s ground-breaking Deep Field and Ultra Deep Field images. And it’s only getting started.

True to its main science objectives, the JWST has peered back in time to the Universe’s earliest galaxies looking for clues to how they assemble and evolve.

December 12, 2022December 12, 2022 by Evan Gough

Webb Completes its First “Deep Field” With Nine Days of Observing Time. What did it Find?

This image taken by the James Webb Space Telescope highlights the region of study by the JWST Advanced Deep Extragalactic Survey (JADES). This area is in and around the Hubble Space Telescope’s Ultra Deep Field. Image Credit: NASA, ESA, CSA, and M. Zamani (ESA/Webb).

About 13 billion years ago, the stars in the Universe’s earliest galaxies sent photons out into space. Some of those photons ended their epic journey on the James Webb Space Telescope’s gold-plated, beryllium mirrors in the last few months. The JWST gathered these primordial photons over several days to create its first “Deep Field” image.